Lubricating oil compositions



Patented Dec. 2, 1952 UNITED STATES PATENT OFFICE LUBRICATING OIL COMPOSITIONS William T. Stewart, El Cerrito, and Alfred Goldschmidt, Oakland, Calif., assignors to California Research Corporation, San Francisco, Calif., a

corporation of Delaware No Drawing. Application December 16, 1950, Serial No. 201,253

wherein n is an integer greater than one and the free valences may be satisfied with hydrogen atoms and/or organic radicals, such as methyl, ethyl, propyl radicals, etc., have hitherto been proposed as synthetic lubricants. These materials may be prepared from ethylene oxide, and the higher 1,2-epoxides, such as 1,2-propylene oxide, the butylene oxides. mixtures of these materials, and the corresponding glycols. As known in the art, the resulting products may be polyoxyalkylene diols or polyalkylene glycol derivatives, in which one or both of the terminal hydroxyl groups have been removed during the polymerization reaction or subsequently thereto, as by etherification or esterification to yield monoor di-ether or monoor di-ester groups or a combination of such terminal groups whereby certain desirable properties are imparted to the final polymeric mixture.

By way of illustration, U. S. Patent 2,448,664 describes the preparation of a polyoxypropylene polymeric mixture according to the equation ROH n(OC2Ha.CHa) R.(OCzHa.CH3)nOH Monohydric 1, 2-propylene Polyoxypropylene alcohol oxide monohydroxy compound These products have molecular weights ranging from about 400 to 2,000 and higher, and are alleged to be useful as synthetic lubricants.

More recently polyoxyalkylene polymeric and copolymeric mixtures containing polymer units having more than two carbon atoms separating oxygen atoms in the polymer chain have been prepared and described. For example, U. S. Patent 2,520,733 describes the preparation of polymers and copolymers derived from trimethylene glycol.

The foregoing compounds, as well as additional polymeric materials contemplated by the invention, are further described in U. S. Patent 2,491,432.

'istics of blends of polyalkylene glycol polymeric As compared with mineral oils, the polyalkylene glycols possess certain superior properties, as a result of which they would be more extensively used but for their high cost. For example, the polyalkylene glycols have higher viscosity indices, and lower pour points than mineral oils of comparable viscosity. A further additional property is that upon oxidation they tend to decompose into harmless volatile materials rather than to form complex insoluble engine deposits,

their use in engine lubrication thus resulting in greater engine cleanliness.

It is also known that in general additives conventionally employed in combination with a mineral oil to improve one or more properties thereof, such as oxidation and corrosion inhibitors, detergents, and the like, are often with-' out effect when combined with the polyalkylene glycol polymers. Another disadvantage of polyalkylene glycol polymers is their limited solubility in mineral oils. At relatively high temperatures, blends of mineral oil and polyalkylene glycol polymer show phase separation.

, Notwithstanding the poor miscibility charactermaterial and mineral oil, the blends are capable of manifesting the desirable properties of the polymers. Moreover, certain conventional mineral oil additives have been found desirably to affect the polymer when incorporated in the polymeric material in the presence of mineral oil. For a number of reasons, therefore, and for the further reason of economy, it is desirable to form blends of mineral oil and polyalkylene glycol polymeric material having improved miscibility characteristics.

Now, in accordance with the invention, it has been found that the miscibility characteristics of blends of mineral oil and polyalkylene glycol polymeric material can be improved substantially by the bringing together of mineral oil and said polymeric material in the presence of a small amount of a polar compound. More specifically, it has been found that the miscibility temperature, more fully hereinfater described, of mixtures or blends of mineral oil and polyalkylene glycol polymer can considerably be lowered by the incorporation in a blend or mixture of the aforesaid components of a small amount of a carbonylcontaining compound, such as carboxylic acids, ketones, aldehydes, etc.

More particularly, the carbonyl-containing compound contemplated by the invention is one that contains at least five aliphatic carbon atoms, and is compatible with or unreaotive to- 3 ward polymer and/or mineral oil. Materials such as acyl chlorides, which are reactive with the basic components of the blends, are therefore excluded. Suitable materials on the other hand are carbonyl-containing compounds such as acids of, thegeneral, formula 1? ao-on esters, represented by the formula I? RC-OR ketones, having the general formula.

BALE

and aldehydes of the general formula a t-n Moreover, suitable carbonyl-containing compounds are those in which the groups represented by Ror R in the above formulas are free of polar substituents, such as nitro or halogen radicals. These polar radicals by imparting additionalpolarity to the molecule adversely affect the solubilizing effect of the carbonyl-containing compound in systems of the type described. On the-other hand, carbonyl-containing compounds havingv substituent groups of substantially no polarity, for example, a benzene ring, consisting of the elements hydrogen and carbon are permitted. Thus, the carbonyl group may be attached to alk yl; alicyclic, alkaryl' or arylalkyl groups, the alkyl portion of which has at least five carbon atoms.

In general, the greater the number of carbon atoms: in the carbonyl compound, the more pronounced'the solubilizing effect imparted to the mixture of mineral oil and polymer. Therefore, carbonyl-containing compounds having 18, or

more, carbon atoms in the molecule are suitable in carrying out the invention. Since, however, the presence of aromatic carbon, e. g., a benzene ring,*contributes substantially no solubilizing effect' to' the'molecule, it is accordingly ignored in determining the effective, carbon atoms in the molecule.

Specific examples of carbonyl-containing compounds'which can be employed in accordance with the invention are n-caproic acid; cyclohexylpropionic acid; n-capric acid; oleic acid; nonanoic acid, more particularly, 3,5--trimethylhexanoic acid; n-propyl acetate; ethyl propionate; isopropyl acetate; n-butyl acetate; ethyl-n-butyrate; isoamyl acetate; amyl acetate; methyl; caproate; n-butyl oleate; heptadecyl acetate; dihexylorthophthalate; dinonyl orthophthalate; dicapryl orthophthalate; di-n-butyl oxalate; di-n-butyl succinate; di-n-butyl sebacate-;; dicapryl sebacate; cetylphenoxy propyl acetate; heptaldehyde: valeraldehyde; caprylic aldehyde; capric' aldehyde; undecylaldehyde; methyl-n-hexyl ketone; methyl-n-nonyl ketone; 2,2,5,5-tetramethylhexanone; 2,6-dimethyl heptanone-4, and methyl n-octyl ketone;

It has been foundthat the amount of carbonyl compoundreouired to effect an improvement in the,' miscibilitycharacteristics of polyalkylene glycolpolymer and mineral oil blends is substantially independent of the proportions of mineral oil andpolymer within arange of about to about 80% by volume of either. component. That is, either. component can be present in the composition. in. an amountof about. one-fourth to about four-fold the amount by volume of the other component, although for practical purposes an equal amount of either component is preferred. In general, the amount of solubilizing compound can vary from an amount of about 1% to about 10% by volume of the finished composition, an amount of about 2% to 5% being preferred. While greater amounts than about 10% can be employed, such amounts are not particularly desirable because they adversely affect the properties of the finished composition, such as viscosity index.

In order toobtain quantitative data on the effectiveness of the solubilizing agent to improve the miscibility of polymer and mineral oil, the following method and apparatus were employed: a double-walled test tube, having an inside diameter-of about 11 mm., an outside diameter of about 12 mm., and being about 9 cm. long, is provided with a cork stopper, and fitted with a thermometer. Sufficient sample is placed in the tube to cover, the bulb of the thermometer (about 2 cc.), after which the test tube with contents,

is placed, in a suitable cooling bath, the contents of the, tube being continuously stirred with the thermometer. Phase separation is manifested by a sudden cloud formation, and the temperature at which the cloud appears is noted, and recorded as the miscibility temperature.

The following examples are given to illustrate compositions prepared in accordance with the invention:

A mixture of polyalkylene glycol polymer material and mineral oil was prepared by mixing equal parts, by volume, of the polymer and mineral oil. The polymer was prepared from 1,2- propylene oxide and 2-ethylhexanol, and had a viscosity of 61,2 SSU at 210 F. The mineral oil was a distillate cut obtained from naphthenic base crude, treated with aqueous phenol, sulfuric acid and percolated through Fullers earth, and had a viscosity of 65.9 SSU at 210 F.

To portions of the foregoing mixture there was added separately the solubilizing compoundsindicated below, said compound in all of the tabulated examples being added in an amount of 10 per cent by volume of the finished composition. After the incorporation of the solubilizing compound the miscibility temperature, as tabulated below, was noted and recorded.

M iscibility Example Solubilizing Compound Temperature, F.

None h 60 n-Caproic acid Cyclohexyl prop Example 20 A composition consisting of volume per cent of the polymer and 20 volume per cent of the oil employed in the examplestabulated above had a miscibility temperature of 19 F. Addition of 10 per cent by volume of the composition of oleic n-Capric acid l8 3,5,5-Trlmetl1ylhexanoic acid. 20 Oleic acid -2 n-Butylacetatc". 39

Ethyl-n-butyrata. 40

. Isoamy1acctate. 30

n-Amylacetate.-. 32

Methyl caproate 28 n-Butyl oleate 21 Heptadecyl acetate 20 Dicapryl orthophthalate 30 Dicaprylsebacate 27 n-Heptaldehydc 40 Undeoy1aldehyde 30 Methyl-n-hexyl ketonc 45 Methyl-n nonyl ketone 40 acid resulted in a composition having a miscibility temperature of 20 F.

On the other hand, 20 volume per cent of the same polymer and 80 volume per cent of the same oil resulted in a composition having a miscibility temperature of 53 F. Addition of volume per cent of oleic acid lowered the miscibility temperature to 0 F.

Example 21 To equal proportions, by volume, of the polymer employed in obtaining the data tabulated above, and of a mineral oil having a viscosity of 60.6 SSU at 210 F. there was added 10 volume per cent of oleic acid. The blend of mineral oil and polymer alone had a miscibility temperature of 123 F., whereas the finished blend had a miscibility temperature of 52 F. The mineral oil in this example was derived from a phenol, cresol and propane treated residuum of an intermediate base crude to give a waxy raffinate. The rafiinate was dewaxed by means of methyl ethyl ketone, the dewaxed oil treated with clay and then fractionated to yield the finished oil.

Example 22 -Polyalkylene glycol polymeric material was prepared from methanol and 1,2-propylene oxide and subsequently esterified with acetic anhydride, the finished polymer having a viscosity of 40.0 SSU at 210 F. To this there was added an equal volume of a spray oil having a viscosity of 34.1 SSU at 210 F. This resulted in a composition having a miscibility temperature of 30 F. Addition of 10 volume per cent of oleic acid resulted in a composition having a miscibility temperature of 10 F.

Example 23 A composition consisting of 45 volume per cent of the oil described in the example immediately above and 45 volume per cent of the 2-ethylhexanol initiated polymer employed in obtaining the tabulated data, and 10 volume per cent of heptadecyl acetate had a miscibility temperature of 70 F. Polymer and oil in equal proportions without the alcohol had a miscibility temperature of 0 F.

Example 24 A polymer was prepared from a mixture consisting of equal mol per cent proportions of ethylene oxide and 1,2-propylene oxide, employing octanol to initiate the polymerization reaction. The resulting polymer was esterified with acetic anhydride, the octanol-initiated ethylene oxide-propene oxide acetate polymer having a viscosity of 40.0 SSU at 210 F. This polymer was mixed with an equal volume of a mineral oil having a viscosity of 89.7 SSU at 210 F. and obtained from a naphthenic crude distillate treated with aqueous phenol, sulfuric acid and clay. The blend of polymer and oil had a miscibility temperature of 8 F. Addition of 10 volume per cent of n-heptaldehyde resulted. in a finished composition having a miscibility temperature of -25 F.

Example 25 A water-initiated polypropene oxide polymer having a viscosity of 62.0 SSU was blended with an equal amount of a spray oil having a viscosity of 36.6 SSU at 210 F. The miscibility temperature of the blend was 120 F. Addition of 10% by volume of the blend of methyl-n-nonyl ketone resulted in a composition having a miscibility temperature of 92 F.

6 Erample 26 A polymer was prepared from stoichiometric proportions oi ethylene oxide and isobutylene oxide, employing 2-butanol to initiate the poly merization reaction, the polymer being subsequently esterified with acetic anhydride to yield a product having a viscosity of 48.6 SSU at 210 F. Equal proportions of this polymer with the oil used in the tabulated examples gave a composition having a miscibility temperature of 82 F. Addition of 10% by volume of the blend of oleic acid resulted in a composition having a miscibility temperature of 5 F.

As indicated in the foregoing examples, the mineral oil can be any hydrocarbon oil of lubricating oil viscosity. It can be a straight mineral oil or a distillate derived from parafiinic, naphthenic, asphaltic or mixed base crudes. Moreover, the oil may be one refined by conventional methods, such as solventor acid-treated oils or mixtures thereof. Also satisfactory for purposes of the present invention are synthetic oils such as those derived from the polymerization of olefins or the Fischer-Tropsch process. Various blended oils are also contemplated by the invention.

Obviously many modifications and variations of the invention, as hereinbefore set forth, may be made without departing from the spirit and scope thereof, and, therefore, only such limitations should be imposed as are indicated in the appended claims.

We claim:

1. Lubricating oil composition comprising a major proportion of a blend of hydrocarbon oil and polyalkylene glycol polymeric material of lubricating oil viscosity in an amount, by volume, of about one-fourth to about four-fold the amount of said hydrocarbon oil, and a minor amount, sumcient substantially to lower the miscibility temperature of said blend, of at least one carbonyl-containing material selected from the group consisting of the materials represented by the formulas and wherein R and R are radicals selected from the class consisting of alkyl, alkaryl, arylalkyl, and alicyclic radicals, said radicals being free of polar substituents, and said carbonyl-containing material having at least 5 aliphatic carbon atoms in the molecule, and being soluble in said blend at the miscibility temperature of said blend.

2. Composition substantially as described in claim 1, wherein the hydrocarbon oil is a mineral oil.

3. Composition substantially as described in claim 2, wherein the polyalkylene glycol polymeric material is a 1,2polyalkylene glycol polymeric material and has at least one terminal group selected from the group consisting of ether and ester groups.

4. Composition substantially as described in claim 2, wherein the carbonyl-containing material is one represented by the formula 7. wherein R is a radicalselected from the class consisting of alkyl, alkaryl, aryl-alkyl and alicyclic radicals, said radical being free of polar substituents.

5; Composition substantially as described in claim 2, wherein the carbonyl-containing material is one represented by the formulaf ao oa' wherein Rand R are radicals selected from the class consisting of alkyl, alkaryl, arylalkyl, and alicyclic radicals, said radicals being free of polar substituents.

6. Composition substantially as described in claim 2, wherein the carbonyl-containing material isone represented by the formula,

I! RC-R wherein R and R are radicals selected from the class consisting of alkyl, alkaryl, arylalkyl, and alicyclic radicals, said radicals being free of polar substituents.

7. Composition substantially as described in claim 2, wherein the carbonyl-containing material is one represented by the formula wherein R is a radical selected from the class consisting of alkyl, alkaryl, aryl-alkyl and alicyclic radicals, said radical being free of polar substituents.

8. As a composition of matter, a blend of mineral lubricating oil and 1,2-polypropylene glycol polymeric material of lubricating oil viscosity in an amount, by volume, of about onefourth to about four-fold the amount of said mineral oil, said blend containing in addition a minor amount, sufiicient substantially to lower the miscibility temperature of said blend, of at least one carbonyl-containing material selected from the group consisting of the materials represented by the formulas n on, n o R, RtLa' and o Iii-H wherein R and R are radicals selected from the class consisting of alkyl, alkaryl, arylalkyl, and alicyclic radicals, said radicals being free of polar substituents, said carbonyl-containing material having at least aliphatic carbon atoms in the molecule and being soluble in said blend at the miscibility temperature of said blend.

9. Composition substantially as described in claim 8, wherein the 1,2 polypropylene glycol material has at least one terminal group selected from the class consisting of ether and ester groups.

10; Composition substantially as described in claim 9, wherein the 1,2 polypropylene glycol polymeric material has a terminal ether group.

11. Composition substantially as described in claim 10, wherein the carbonyl-containing materialis one represented by the formula i RC-OE wherein R is a radical selected from the class consisting of alkyl; alkaryl, aryl-alkyl and alicyclic radicals, said radical being free of polar substituents.

12. Composition substantially as described in claim 10, wherein the carbonyl-containing material is one represented by the-formula ll RC-O R wherein R; and R are radicals selected from theclass consisting of alkyl, alkaryl, arylalkyl, and" alicyclic radicals, said radicals beingfree of polar substituents.

13. Composition substantially as described in claim 10, wherein the carbonyl-containing material is one represented by the formula 0 ll RC-R wherein R and R are radicals selected from the class consisting of alkyl, alkaryl, and alicyclic radicals, said radicals being free of polar substituents.

14. Composition substantially as described in claim 10, wherein the carbonyl-containing material is one represented by the formula H RCH whereinR is a radical selected from the class consisting of alkyl, alkaryl, aryl-alkyl and alicyclic radicals, said radical being free of polar substituents.

WILLIAM T. STEWART. ALFRED GOLDSCHMIDT.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,481,278 Ballard et a1. Sept. 6, 1949 2,510,540 Ballard et al. June 6, 1950 2,520,733 Morris et a1. Aug. 29, 1950 2,543,735 Stewart et al. Feb. 27, 1951 OTHER REFERENCES Ucon Fluids and Lubricants, Carbide and Carbon Chem. Corp, New York, N. Y., May 31, 1938, pg. 14 and 15. 

1. LUBRICATING OIL COMPOSITION COMPRISING A MAJOR PROPORTION OF A BLEND OF HYDROCARBON OIL AND POLYALKYLENE GLYCOL POLYMERIC MATERIAL OF LUBRICATING OIL VISCOSITY IN AN AMOUNT, BY VOLUME, OF ABOUT ONE-FOURTH TO ABOUT FOUR-FOLD THE AMOUT OF SAID HYDROCARBON OIL, AND A MINOR AMOUNT, SUFFICIENT SUBSTANTIALLY TO LOWER THE MISCIBILITY TEMPERATURE OF SAID BLEND, OF AT LEAST ONE CARBONYL-CONTAINING MATERIAL SELECTED FROM THE GROUP CONSISTING OF THE MATERIALS REPRESENTED BY THE FORMULAS 